• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.6
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• pp.51-63
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• 2023

To improve the problem that the settlement curve of the consolidation theory of Terzaghi does not match well with the actual settlement curve, we included a secondary compression settlement and analyzed it by varying the beginning point and then obtained the following results. The current methods of calculating the compression index from the  log𝜎 curve and the coefficient of consolidation from the time-dependent settlement curve for each consolidation pressure proved that the final settlement amount will be consistent after a long time, but the actual settlement amount will always be smaller than the predicted settlement amount during the settlement progress stage. The consolidation factors estimated by the curve fitting with the condition that the secondary compression begins in the second half of the primary compression showed similar values to the consolidation factors estimated by the curve fitting for the primary compression only, and the settlement curves were in better agreement throughout the compression. It showed different values, showing low validity. It can be inferred that secondary compression acts from the point when a significant portion of the excess pore water pressure is dissipated, and the loading stress begins to have more influence on the skeletal structure of the soil. Analysis results show that secondary compression begins at the range of 91 % to 98 % on the average degree of primary consolidation.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.97-102
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• 2000

This paper presents the design, construction and performance of ground treatment to support road embankment on refuse landfill. Long-term settlement of refuse landfill is analysised by Sower and Yen/scanlon. As a results of site test, predicting settlement excess the allowable settlement and ultimate bearing capacity is not satisfied. The effectiveness of DDR(Deep Dynamic Replacement) is monitered by field tests (SPT, PBT, PMT) before, during and after construction of the stone columns. The ultimate bearing capacity for reinforced landfill by stone columns obtained from the in-situ test results has been compared with the existing theories. In municipal wastes landfill, settlement after treatment using stone column is satisfied to allowable residual settlement. Therefore, long-term stability can be gain in these cases.

• Coupled systems mechanics
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• v.3 no.2
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• pp.233-245
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• 2014

Coupled finite element analysis is carried out to study the effect of degree of saturation on the vertical displacements and pore water pressures simultaneously by developing a FORTRAN90 code. The finite element formulation adopted in the present study is based upon Biot's consolidation theory to include partially saturated soils. Numerical methods are applied to a two-dimensional plane strain strip footing (flexible) problem and the effect of variable degree of saturation on the response of excess pore water pressure dissipation and settlement of the footing is studied. The immediate settlement in the case of partly saturated soils is larger than that of a fully saturated soil, the reason being the presence of pore air in partially saturated soils. On the other hand, the excess pore water pressure for partially saturated soil are smaller than those for fully saturated soil.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1243-1251
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• 1994

The implicit finite difference program was developed to evaluate the relationship between time and consolidation ratio within the zone of vertical drain effective radius. In the evaluation, the excess pore water pressure was considered to dissipate in two directions, namely, vertical and radial flow direction. To calculate subsoil stress increments in the soil due to multi-step embanking, the foundation soil was assumed to be an isotropic and homogeneous elastic medium and the initial excess pore water pressure was estimated by using Skempton's parameters whose condition is plane strain and elastic phase of pore pressure response within the soft ground. Regarding to the settlement estimation, immediate and primary consolidation settlements were calculated. The secondary or delayed consolidation settlement was not considered. Numerically calculated excess pore water pressure and settlements were similar to the measured data in situ. Thus, this method can be used to predict the time-consolidation ratio of each layer treated by vertical drain method.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.313-316
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• 2002

This study was performed to evaluation the consolidation behavior of agricultural reservoir in the very soft ground. The final settlement prediction methods by Hyperbolic and Asaoka methods were used to compare with the degree of consolidation estimated by exess pore water pressure. The dissipated excess pore water pressure during embankment construction and peak excess pore water pressure on the completed embankment were suggested for the estimation of the degree of consolidation. It was concluded that the degree of consolidation estimated from dissipated excess pore water pressure was more reliable than that from the peak excess pore water pressure.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.1
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• pp.67-75
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• 2024

In the case of the Pohang earthquake, which had a magnitude of 5.4 in 2017, geotechnical damages such as liquefaction and ground settlement occurred. The need for countermeasures has emerged, and experimental research in the Pohang area has continued. This study collected undisturbed samples from damaged fine-grained soil areas where ground settlement occurred in Pohang. Cyclic tri-axial tests for identifying the dynamic characteristics of soils were performed on the undisturbed samples, and the results were analyzed to determine the cause of ground settlement. As a result of the study, it was determined that in the case of fine-grained soils, ground settlement occurred because the seismic load as an external force was relatively more significant than the shear resistance of the very soft fine-grained soils, rather than due to an increase in excess pore water pressure.

• Geotechnical Engineering
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• v.9 no.3
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• pp.77-90
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• 1993

In the settlement analysis of shallow foundation soil properties, loads and soil strata involve many uncertainties so it is necessary to do analysis of settlement that considers the probabilistic properties of each variable. This study is performed to probabilistic analysis for settlement of shallow foundation consisted of individual footings by using Monte Carlo Method. To consider the uncertainty of variables, both the soil properties and loads are assumed to be normal distribution random variables and get settlement mean and coefficient of variation of individual footing. And the settlement of each individual footing is also assumed to be normal distribution. Settlement of each individual footing which considers the probability of soft soil pockets in soil strata follows Markov process. Then it is performed to do sensitivity analysis which is involved to excess probability of allowable criteria of maxi mum settlement and differential settlement according to varity of each variable. It is thought to be proper that the settlement analysis of shallow foundation should be analyzed considering uncertainty of variables and soil stratum conditions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.2
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• pp.60-72
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• 1992

This study aims at predicting the behavior of saturated soft clayey foundation subjected to earth structure loads such as tidal dike, embankment etc. by using Biot's consolidation equation coupled with elasto-viscoplastic constitutive model. To validate the computer program developed b author, a case study was performed for the site of Kwang-yang steel works improved by sand drain, where since the beginning of the works, field measurements(settlement, lateral displacement and excess pore water pressure) had been accurately achieved. Comparisons between numerical results and observation values were carried out. The main results obtained are summarized as follows : 1. Settlement and lateral displacement between numerical and observation values show satisfactory accordance. 2. As for the exess pre water pressure, numerical results appear to be larger than observation values, which may be due to the existence of sand seams which were not found during soil investigation. 3. Useful data available for failure prediction of soft foundation can be secured by examining lateral displacement, settlement, exess pore water pressure and stress paths.

• Geomechanics and Engineering
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• v.4 no.2
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• pp.91-103
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• 2012

Focusing on the effect of excess pore pressure dissipation on liquefaction-induced ground deformation, a series of 1-g shaking table tests were conducted in a rigid soil container by use of saturated Toyoura sand, the relative density of which was 20-60%. These tests were subjected to the sinusoidal base shaking with step increased accelerations: 100, 200, 300 and 400 Gals for 2-4 seconds. Shaking table tests were done using either water or polymer fluid with more viscous than water, thus varying the sand permeability of model tests. Excess pore pressures, accelerations, settlements and lateral deformations were measured in each test. Test results are presented in this paper and the effect of sand permeability on liquefaction and liquefaction-induced ground deformation was discussed in detail.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2C
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• pp.83-94
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• 2008

In this study an effective stress analysis was performed to evaluate liquefaction potential and ground settlement for reclaimed sites. The effective stress model can simulate the stiffness degradation due to excess pore pressure and resulting ground deformation. It is applicable to a wide range of strain. An equivalent linear analysis suitable for low strain levels was also carried out to compare the effective stress analysis. Shear stress ratio calculated from an equivalent linear analysis was used to determine SPT blow count to prevent liquefaction. Depending on the magnitude of potential earthquake and fine contents, the SPT blow count was converted into an equivalent cone tip resistance. It was compared with the measured cone tip resistance. The measured elastic shear wave velocity and cone tip resistance from two reclaimed sites in Incheon were used to perform liquefaction analyses. Two liquefaction evaluation methods showed similar liquefaction potential which was evaluated continuously. The predicted excess pore pressure ratio of upper 20 m was between 40% and 70%. The calculated post-shaking settlement caused by excess pore pressure dissipation was less than 10 cm.